1. Field of the Invention
This invention relates to a press-connecting terminal having press-connecting blades into which a wire is press-fitted to be electrically connected thereto, and more particularly to a press-connecting terminal in which the press-connecting blade is prevented from deformation when the wire is press-fitted into this blade.
2. Related art
Usually, sensors and electronic devices for various controls are mounted on an automobile, and the sensors are connected to the electronic devices through an automobile wire harness. Therefore, the number of connections between the electronic devices and wires, as well as the number of connections between the wires, is naturally large. Therefore, in order to enhance the efficiency of assembling of the automobile and also to facilitate the disassembling and assembling for maintenance purposes, press-connecting connectors capable of easily connecting the wires together are commonly used. Press-connecting terminals each having a press-connecting blade are attached to the press-connecting connector, and then the wire is press-fitted in the press-connecting terminal.
One conventional press-connecting terminal for use in such a press-connecting connector, as disclosed in U.S. Pat. No. 4,385,794, will now be described. As shown in FIG. 9, the press-connecting terminal 1 is formed by blanking and bending an electrically-conductive metal sheet. This terminal 1 has a press-connecting portion 2 of a U-shaped transverse cross-section formed at a generally central portion thereof in its longitudinal direction. A clamping portion 3 for clamping and holding a wire is provided at one end of the terminal while a connection portion 4 for connection to a mating terminal is provided at the other end of the terminal.
More specifically, slit-like press-connecting blades 5a and 5b are provided at front and rear ends of the press-connecting portion 2, respectively. For connecting the wire, the sheathed wire is press-fitted into the press-connecting portion in a direction of arrow A, so that the press-connecting blades 5a and 5b cut the wire sheath to be electrically connected to the wire. The thus connected wire is clamped by the clamping portion 3 against disengagement. The mating terminal is inserted into an open portion 4a of the connection portion 4, and is electrically connected to a resilient contact piece portion 4b.
Another press-connecting terminal (different from the above terminal) as disclosed in Japanese Utility Model Unexamined Publication No. 60-142463 will now be described with reference to FIGS. 10 and 11.
As shown in FIG. 10, this press-connecting terminal 11 is formed by blanking and bending an electrically-conductive metal sheet. This terminal 11 has a press-connecting portion 12 formed at a generally central portion thereof in its longitudinal direction. A clamping portion 13 for clamping and holding a wire is provided at one end of the terminal while a connection portion 14 for connection to a mating terminal is provided at the other end of the terminal.
More specifically, the press-connecting portion 12 includes a bottom plate 12a, opposite side plates 12b bent upright respectively along opposite sides of the bottom plate 12a, and a pair of opposed sheet-like contact piece portions 15 which are formed by stamping and bending front and rear portions of the bottom plate 12a, upright, with the central portion of the bottom plate 12a, remaining intact. Each sheet-like contact piece portion 15 has a contact slot 16 open to its upper edge. The two sheet-like contact piece portions 15 and the central portion 12a, of the bottom plate, continuous therewith, jointly assume a cross-sectionally U-shape. A pair of tabs 17, formed respectively on opposite sides of each sheet-like contact piece portion 15 at an upper portion thereof, are engaged respectively in notches 18 formed respectively in the opposite side plates 12b and 12b, thereby preventing the contact piece portion 15 from falling in the longitudinal direction.
For connecting the wire 19, the sheathed wire 19 is press-fitted into the contact slots 16, so that edges of the contact slots cut the wire sheath to contact a conductor 20 of the wire, as shown in FIG. 11.
In the construction of the above press-connecting terminal 1, during the time when the wire is press-fitted into the press-connecting portion 2, there develops a force tending to expand or open the whole of the press-connecting portion 2 as the press-connecting blades 5a and 5b cut the wire sheath. If this occurs, the contact of the press-connecting blades 5a and 5b with the conductor is incomplete, and therefore a plurality of recesses 6 are formed in the bent portion by a punch or the like, thereby preventing the expansion of the press-connecting portion 2. However, such expansion can not be sufficiently prevented only by the recesses 6, thus inviting a problem that upon application of a large force, the press-connecting portion 2 is expanded or opened.
In the construction of the above press-connecting terminal 11, the opposite side plates 12b are bent upright to form, together with the bottom plate, the U-shaped cross-sectional configuration to support the tabs 17, thereby preventing the expansion or opening of the contact piece portion 15 (having the contact slot 16) in directions B upon press-fitting of the wire.
If the press-connecting terminal 11 is designed into a small size, or if a wire of a large diameter is press-fitted into the press-connecting terminal 11 without increasing the size of this terminal, it is necessary to reduce a width W1 of a half portion of the contact piece portion 15. However, the thickness of the conductive metal sheet is about 2 mm at best, and if the overall width W0 of the press-connecting terminal 11 is 15 mm, and the width of the slit is 5 mm, then the width W1 is 2.5 mm, and a clearance is 0.5 mm. Therefore, the blanking formation becomes difficult. In the press-connecting terminal 11 of this construction, the compact design is limited by the width W1.